I'm using TeXstudio 2.12.8 and I was using the software with the standard configuration and options.
I wanted to show line numbers in editor window, so I followed this link: texstudio: show line numbers in editor.
For this, it's resolved as I want. However, after this my editor window fixed the text width until the vertical line in image above, and I don't know how to return to a variable width controlled by the entire size of the window.
I think that I did this accidentally, but I didn't find the option in "Configure TeXstudio" menu to correct this. Can you help me?